Manufacture of hard odorless soap from low grade fats and oils



2,739,163 Patented Mar. 20, 1956 MANUFAGTURE or HARD DDORLESSTSDAP FROM LOW GRADE FATS ANnmL-s Klaus Appulm, Vina del Mar, Chile, assignorto com pania IndustriaL Vina del Mar,hile, a corporation of Chile No Drawing. Application April a, 1 95;,

Serial No. 346,803

- Claims-priority, application GreatBritain July 11, 1952 6 Claims. (or. 260-413 V This invention relates to the manufacture of odorless soap of. good quality from low grade animal or vegetable oils and fats which have a disagreeable odor...

Soaps of good quality are usuallyma-nufactured from saturated fatty acids which contain from 12 to 16 carbon atoms in the chain, as for instance those fatty acids predominating in coconut oil. 1 3

The majority of fatty substances found in nature are formed by fatty acids of a longer chain than 16 carbon atoms or are highly unsaturated, or by a combination of both types of substances and are consequently less suitable for the manufactureof good quality soaps. They are the so-called low-grade'fats andoils.

In my co-pending application, Serial No. 151,030, filed March 21, 1950, now Patent No. 2,640,840, there is described a continuous process for the manufacture of odorless soap of high quality, from low grade animal or vegetable oils and fats, which process comprises the treatment of the fatty acids .derived from low grade oils and fats with molten alkali at about 300 C. in the absence of water and at substantially atmospheric pressure. When the fatty acids used in said process are obtained from malodorous fats and oils by special reagents according to the Twitchell process, the subsequent saponification reaction with molten'alkali at high temperature results in the formation of excessive and persistent foam. This necessitates resorting to a number of precautions before the reaction canbe carried out in an industrially profitable manner. One such precaution was to add sperm oil to the fatty acids to reduce the foaming.

in laboratory trials a remarkable difference has been noted between the fatty acids produced by refining fats and those obtained by splitting with Twitchell type reagents as far as consistency and formation of foam during anhydrous saponification is concerned. It has been observed that the foam formed during anhydrous saponification of fatty acids produced by refining was less viscous and dense than the foam formed when submitting to the same treatment, fatty acids obtained by splitting with Twitchell. type reagents. This difference in behavior suggested the possibility of saponifying by the anhydrous saponification system, those fatty acids produced by refining without addition of a reaction moderator such as sperm oil. The difference in behavior of these two types of fatty acids, suggested what has not been possible to prove by analysis, namely, that the remainders or traces of the reagent retained in the fatty acid obtained by the Twitchell process, due to their emulsifying properties conferred consistency and persistency to the foam, thus making continuous anhydrous saponification impracticable.

I have now found that the foam formation can be moderated to such an extent that it is possible to carry out the saponification reaction in a continuous manner without special precautions, if the fatty acids obtained by the Twitchell process are first treated with activated carbon. The fatty acids may be treated with about 0.2% of their weight of activated carbon, preferably after first "2 treating them with bleaching earth, for example, with about 2%. of their weight of bleaching earth. One method of carrying out the process according to the present invention given by way of example is as follows:

A .mixture of fatty acids obtained by splitting malodorous oils and fats by the Twitchell process are vacuum dried, treated with 2% of their we'ight ofbleaching earth and then with 02% of activated carbon and finally filtered in a filter-press. The resultant fatty. acids at a temperature slightly above their melting point, and the alkali in molten state, are simultaneously passed in controlled amounts to a specially constructed saponifier such, for example, as described in U. S. Patent No. 2,492,940,

' where they are reacted at a temperature of about 300- 350 C. The reaction between the fatty matter and alkali takes pla'ee instantaneously resulting in "complete saponification with the liberation of hydrogen. The soap leaves the continuous saponifier continuously, passing through an automatic outlet in the same proportion as it is fed in with the raw'material. The hydrogen liberated during the process passes through a condenser for its purification, and finally through an outlet arrangement (water seal) which maintains a slight uniform pressure of not more than 20 cm. water in the whole system, in order to prevent the entrance of air. Consequently, by treating with activated carbon the fatty acids obtained by the Twitchell process, such fatty acids are rendered suitable for anhydrous saponification, without the addition of a reaction moderator such as sperm oil, as set forth in my aforementionedpatent application.

.I Thus, a new-processhas been *developed for obtainingv excellent quality soaps from fatty acids of marine animal fats and oils or from other sources which hitherto, due

to their high content of unsaturated fatty acids, had been of no importance to the soap industry.

Additional examples are given below of how this process was carried out in practical elaborations in an industrial plant.

Example 1 The raw materials used were fatty acids obtained from whale oil by a Twitchell type reagent and treated with activated carbon. The chemical characteristics of these fatty acidswerei saponification index 189.5 Iodine number 125.1

After saponifying these fatty acids by the continuous anhydrous alkali method with 18.7% of molten alkali at 330 C., a neutral hard, odorless soap of good quality was obtained having the following characteristics of its total fatty acids:

saponification index 205.7 Iodine number 51.9

As may be appreciated, the iodine number decreased by about 73 units, this being due to the fact that the long and non-saturated carbon chains were broken and transformed into shorter and more saturated compounds."

Example 2 In another trial, fatty acids obtained from the refining of sunflower oil were used as raw material and treated as in Example 1, using 20% molten alkali. A neutral and excellent quality soap was also obtained. The iodine number of the fatty acids decreased from 134.0 in the raw material to 80.6 in the fatty acids of the soap and the saponification index increased from 188.1 to 199.0.

Example 3 Fatty acids obtained frornfish oil by a Twitchell reagent were used as raw material and treated as in Example 1. The chemical characteristics of these fatty acids were:

Saponification index 139.8

. iodine number 158.9

Saponification index 204.7 Iodine number 69.5

From the foregoing examples it will be appreciated that whatever percentage of alkali was employed a neutral soap was obtained and the variations are shown by the greater or lesser decrease of the iodine number and corresponding increase of the saponification index.

What I claim is:

1. A continuous process for the manufacture of hard, odorless soaps from highly unsaturated long chain fatty acids produced from low grade or marine animal fats and oils obtained by splitting such fats and oils by a Twitchell reagent, said process comprising, treating said fatty acids with activated carbon, then anhydrously saponifying such treated acids at a temperature between 300 and 350 C. with an excess of molten alkali at substantially atmospheric pressure.

2. A process according to claim 1 wherein the activated carbon is used in about the proportion of 0.2% of the weight of the fatty acids.

3. A process according to claim 1 wherein the fatty 4 acids are treated with bleaching earth prior to treatment with the activated carbon.

4. A process according to claim 3 wherein the bleaching earth is used in about the proportion of 2.0% of the weight of the fatty acids.

5. A continuous process for the manufacture of hard, odorless soap from highly unsaturated long chain fatty acids produced from low grade ormarine animal fats and oils obtained by splitting such fats and oils by a Twitchell reagent, said process comprising'treating said fatty acids with bleaching earth in about the proportion of 2.0% of the weight of the fatty acids, then treating the fatty acids with activated carbon in about the proportion of 0.2% of the weight of the fatty acids, separating the fatty acids from the treating substances and anhydrousiy saponifying such separated treated fatty acids at a temperature between 300 and 350 C. with an excess of molten alkali at substantially atmospheric pressure.

6. A process according to claim 5 wherein the fatty acids obtained by splitting with a Twitchell reagent are vacuum dried before treatment with the bleaching earth and activated carbon.

References Cited in the file of this patent UNITED STATES PATENTS 1,608,341 Schrauth et al Nov. 23, 1926 2,475,420 Brown et al. July 5, 1949 2,492,940 Schmidt Dec. 27, 1949 2,654,768 Palmer Oct. 6, 1953 OTHER REFERENCES Bailey: Industrial Oil and Fat Products, 2nd edition, 1951, page 656. 

1. A CONTINUOUS PROCESS FOR THE MANUFACTURE OF HARD, ODORLESS SOAPS FROM HIGHLY UNSATURATED LONG CHAIN FATTY ACIDS PRODUCED FROM LOW GRADE OR MARINE ANIMAL FATS AND OILS OBTAINED BY SPLITTING SUCH FATS AND OILS BY A TWITCHELL REAGENT, SAID PROCESS COMPRISING, TREATING SAID FATTY ACIDS WITH ACTIVATED CARBON, THEN ANHYDROUS SAPONIFYING SUCH TREATED ACIDS AT A TEMPERATURE BETWEEN 300 AND 350* C. WITH AN EXCESS OF MOLTEN ALKALI AT SUBSTANTIALLY ATMOSPHERIC PRESSURE. 